These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 1.04 s (backtrack: 0/20).

[ebuild  N     ] dev-libs/libptytty-2.0-r1::gentoo  45 KiB
[ebuild  N     ] x11-misc/xsel-1.2.1::gentoo  51 KiB
[ebuild  N     ] x11-terms/rxvt-unicode-9.31-r4::gentoo  USE="font-styles mousewheel perl -24-bit-color -256-color -blink -fading-colors -gdk-pixbuf -iso14755 -startup-notification -unicode3 -wide-glyphs -xft" PERL_FEATURES="ithreads (-debug) -quadmath" 868 KiB
[ebuild  N     ] x11-misc/urxvt-perls-2.3-r1::gentoo  USE="-deprecated" 15 KiB

Total: 4 packages (4 new), Size of downloads: 977 KiB

The following USE changes are necessary to proceed:
 (see "package.use" in the portage(5) man page for more details)
# required by x11-misc/urxvt-perls-2.3-r1::gentoo
# required by =x11-misc/urxvt-perls-2.3-r1 (argument)
>=x11-terms/rxvt-unicode-9.31-r4 perl